Tamoxifen 'cuts genetic cancer risk'

Tamoxifen may protect against a second tumour

Women who carry genes linked to breast cancer can reduce their risk of developing the disease by taking tamoxifen.

Researchers have found that women who have had breast cancer can cut their chances of developing cancer in the other breast by 50% if they take the drug.

Scientists from the Centre for Research on Women's Health in Toronto led the study which looked at women with the BRCA1 and BRCA2 gene mutation.

These faulty genes are implicated in up to 10% of the 35,000 new cases of breast cancer diagnosed each year in the UK.

The researchers compiled information from 34 centres in eight countries, 384 comparing women with the gene mutations who had cancer in one breast and 209 women with the gene mutations who had cancer in both breasts.

They found that women who had used tamoxifen for between two and four years had a reduced risk of developing a second cancer in the other breast.

The report says that "tamoxifen use for three years on average provided protection for up to 10 years."

Prevention

The study, led by Dr Steven Narod, concludes that "tamoxifen can reasonably be offered to women with BRCA1 or BRCA2 mutations and breast cancer for the prevention of contralateral breast cancer".

But, the team also believes that women who are known to carry the two genes would also benefit from taking tamoxifen to prevent them developing cancer in the first place.

Their report in The Lancet says: "We believe that tamoxifen will also reduce the occurrence of primary cancers in BRCA1 and BRCA2 mutation carriers, and that tamoxifen chemoprevention and other options should be discussed with healthy women who carry BRCA1 and BRCA2 mutations."

Other treatments which reduce the risk of developing a second cancer are chemotherapy and removal of the ovaries.

Evidence of effectiveness is important to enable women to make informed decisions

Jackie Graveney, Breakthrough Breast Cancer

The researchers found that chemotherapy "greatly reduced the risk of diagnosis of contralateral breast cancers within two years of treatment but the risk rose after 10 years".

They believe that the chemotherapy kills off cancers at an early stage before they would normally be detected.

The protective effect of removal of the ovaries is long-lasting, because it reduces oestrogen production which is linked to tumour growth in some cancers.

Jackie Graveney of the charity Breakthrough Breast Cancer said: "This study suggests that tamoxifen is potentially useful in preventing a recurrence in women at genetic risk of breast cancer. Evidence of effectiveness is important to enable women to make informed decisions."